Art of cracking hydrocarbon oils



July 17, 1928.

E. C. HERTHEL ET AL ART OF CRACKING HYDROCARBON OILS 2A Sheets-Sheet 1 Filed Oct. 27, 1927 July 17, 1928.

E. c. HERTHEL Er Al.

ART 0F CRACKING HYDROCRVBON- GILS Filed Oct. 27, 1927 2 Sheets-Sheet 2 QTPML lv E Patented July i7, i928.

UNETE STATES PATENT; oFFicE.

EUGENE C. EER'IHEL .AND THOMAS DE COLON TIFFT, OF CHICAGO,y ILLINOIS, AS-

SIGNORS TO SINCLAIR REFINING COMPANY, OF NEW YORK, N. Y., A CORPORATION OF MAINE.

ART F CRACKING HYDRCABBON OILS.,

Application inea octoberv 27, 1927. serial No. 229,122.

rlhis invention relates to improvements in thc cracking oflheavier and higher boiling hydrocarbon oils such as gas oil, fuel oil and topped crude oil, to produce therefrom lighter and lower boiling hydrocarbon o ils, such as gasoline and gasoline-containing cracked distillates. The invention has s everal important advantages in heat economies, in features of control, in the treatment of 19 particular stocks under particularly advantageous conditions, in obtaining a maximum yield and throughout with a minimum requirement of expensive apparatus designed to operate under high pressures and -1n the g5 maintenance of conditions which permit p rolongation of the useful period of operation without sacrifice of eiiciency.

ln carrying out the present invention, the oil to be cracked is forced in a single'pass through a heating zone into a vaporizing zone being maintained under a super-atmos-V pheric pressure in both the heating zone and the vaporizing zone. In the heating zone, the oil is heated to a cracking temperature by heat exchange with heating gases such as the hot products of combustion from a lireboX in which fuel is burned. Unvaporized oil collecting in this vaporizing zone is withdrawn as a liquid therefrom and discharged into a separate vaporizing zone'mantained under a pressure lower than that prevailing in the first. Vapors, including yvapors of the desired lighter and lower boiling oils are separated in the first vaporizing Zone and are taken ofi' therefrom. Due to the reduction in pressure, a further separation of vapors is effected in the second vaporizing zone and these vapors are taken ofi' and subjected to a refluxing operation to effect separation of the heavier fractions from the lighter fractions, which include constituents suitable as components of the desired gasoline-containing distillate, and intermediate refractory constituents that may advantageously be subjected to further cracking treatment. This refluxing operation is effected and controlled by passing fresh oil in heat exchanging relation with the cracked. vapors, and reflux condensate so produced together with unvaporized constituents of the fresh oil are returned to the heating zone. Vapors escaping uncondensed from this reiuxing operation are condensed in a subsequent condensing operation. r The vapors taken off from the first vaporizing zone, the high pressure vaporizing zone, are subjected to a-separate refluXin operation, which may advantageously be e fected and controlled by the introduction of condensate of the vapors escaping uncondensed from the first mentioned reuxing operation. Vapors escaping from the second mentioned refluxing operation are condensed in a subsequent condensing operation as the desired gasoline-containing vrpressure distillate. Reflux condensate from the second mentioned refluxing operation together with the heavier unvaporized constituents introduced as components of the condensate of vapors escaping from the first mentioned lrefluxing operation are forced in a single pass through a separate heating zone into the second, low pressure, vaporizing zone, being heated to a cracking temperature in the second heating Zone. Thus the introduction of condensate of the vapors escaping from the first mentioned refluxing operation may be regulated to control the second mentioned refluxing operation and at the f same time to effect a redistillation of this condensate, as the lighter constituents contained in this condensate which are suitable as components of the desired pressure distillate product are vaporized and escape from the second mentioned refluxing operation together with the lighter vapors formed in the first or high pressure vaporizing zone.

The temperature to which the hot oil products are heated in the second heating zone and the pressure maintained thereon are advantageously somewhat higher than the temperature to which, and the pressure under which, the hot oil products are heated in the first heating zone. The hotl -products from the second heating zone are discharged directly to the second or low pressure vaporizing zone. The pressure under which the second heating zone is operated is maintained and controlled by a pressure regulating valve located in the discharge connecl tion between the second heating zone and the second or low pressure vaporizing zone.

In one particularly advantageous method ino ' the vapor phase.

practicing the process of the invention, reflux condensate from the reiiuxing operation to which the vapors from the high pressure vaporizing zone are subjected, is forced in av single pass through a second heating zone and heated therein to a temperature suiiiciently high to vaporize and crack the oil in 'lhe hot oil products dis- -lcharged into the low pressure vaporizing refractor zone from the second heating zone, if not already vaporized, are largely vaporized on reduction of pressure as discharged into the vaporizing zone and the heat contained in these hot oil products assists in vaporizin an additional portion of the oil discharge Y directly into the low pressure vaporizing zone v vfrom the high pressure vaporizing zone.

The unvaporized residue produced in the:

second vaporizing zone is not returned to either heating zonepbut isdischarged from' the s stein.

v ere desired a part oit the fresh oil supplied to the system may be introduced di- .rectly to either of the heating zones. It is `advantageous tosupply 'al lighter and more oil to the second heatin zone so 'that y.it will vhe subjected immediate y to the v.more severe cracking conditions maintained therein and thisv lighter and more yrefractory i3@ oil at the same time assists in cessivecarbon formation.

" 'The first 'reiuxing operation is advantageously edected under substantially the pressure prevailing in the' first vaporizing Zone; the second reuxing operation" is carried out under a lower pressurenthat prevailing in the second vaporizing zone, or a lower pressure. v

preventing enlln carrying out the invention, it is adm enough toleave a dus or heavy residue,

which can 'loe removed as a liquid, or it may he carried so far that only colte or a cokey mass remains. laporization in the second v vaporizing zone also may be controlled by regulation of the pressure maintained therein. "llhe vaporizationin the second vaporizing zone is advantageousl edected by the self-,contained heat o the ot oil products discharged thereinto from the lirst Vaporizx qing zone and the second heating zone without further application oit external heat. im The Erst vaporizing zone may also be eaternally heated althougha small amount of heat may be supplied externally if desired to secure a greater degree of Vapor-ization.

Fig. 1 of the accompanying' drawings illustrates pictorially the operation of the process of the invention. The invention' will be fully described in connection with Fig. 2 of the accompanying drawings, which illustrate diagrammatically and conventionally one form of apparatus, adapted for carrying out the invention. y

Referring to Fig. 2, the oil to bel cracked 1s supplied vfrom tank l by the ump 1a. This oil may be introduced into t e reflux` tower 2 through connections 3, 4, and 5 or it may be supplied directly to heating coil 6 through connections 3, 7, and 8, or it may be supplied directly to the heating coil 9 through connections 3, 4, l0, 11, and 12. The heating coil 6 discharges into the high pressure vaporizing chamber 13 through connection 14. The heating coil 9 discharges into thel low pressure vaporizing chamber 25 through connection 28 containing the pressure reducing valve 28".l Vapors from the high pressure vaporizing chamber 13 pass through connection 15 to '.the reflux tower 16. Vapore escaping from reflux tower 16 pass through connection 17 to condenser 18. Reflux condensate from reflux tower 16 passed to tank 19 throu h connection 20 and from thence is force by' the` pump through connections 23 and 12 to the heating coil 9, together` with 'fresh oil supplied through connection 11. Liquid residue collecting in the vaporizing chamber 13 is discharged through connection 24 containing the pressure-regulating valve 26 \to the low pressure vaporizing chamber 25. The pressure-reducing lvalve 26'may be manually Or automatically controlled, for example, it may Y be arranged to operate to maintain a fixed liquid level ,in the high pressurevaporizing chamber 13. Where the vaporization. in the low pressure vaporizingchamber 25 is car- -ried to the point where coke or a coky mass remains, duplicate vaporizing receptacles may be provlded sothat the operation may be carried out in a continuous manner. Va-A ors from the low pressure vaporizing chamber 25 pass through connection 27 to the reflux tower 2, and vapors remaining uncondensed escape from the refiux tower 2 im A throughconnection 29 to condenserI 30. Re-

navarra the condensate from receiver 36 discharged to the tank 39, or both condensates or a part 'of both condensates may be collected in `tank 40 and the composite'condensate so produced supplied' to reux tower 16 by the pump 41 through connection 42. The pressure in the high pressure vaporizing chamber ma be maintained and rerulated by means o the valve 43 in connection 17 between the reflux tower 16 and the condenser 18. The condenser 18 may be operated at atmospheric pressure or at substantially the same pressure prevailing in the reflux tower 16, superatmospheric pressure 'being' maintained therein by means of valve 44 or by means of valves 45 and 46. Superatmospheric pressure may be maintained in the low pressure vaporizing chamber, or the pressure therein regulated, by means of valve 47 orv 48, or by means of suitable valves beyond -the condenser. Liquid residue may be discharged from the low pressure vaporizing chamber 25 through connection 49 controlled by valve 50. In the receivers 35 and 36 the condensed product is separated from any gases or vapors remaining uncondensed and the gases and vapors discharged through connections 51 and 52 respectively.

The heating coils 6 and 9 are arranged in separate heating furnaces 53 and 54 respectively. These furnaces comprise a fire box` heating flues in which the heating coils are arranged, and a stack flue through which waste heating gases escape from the heating fines. Means ma be provided, as shown at 55 and 56, for recirculating through the heating flues with fresh hot products of combustion from the fire box, a portion of the escaping waste heating gases. The provision of separate heatingv furnaces makes possible the separate and independent regulation and control of the heating operations carried out in the two heating coils. Additional heat may be supplied to the high pressure vaporizing chamber 13 by means of the furnace 57, or this chamber may be externally unheated. The low pressure vaporizing chamber 25 and connection 24 between the high pressure vaporizing chamber and the low iressure vaporizing chamber are thoroughly lagged or heat-insulated to prevent heat loss. The high pressure vaporizing chamber, particularly where externally unheated, may also be lagged or heat-insulated in a similar manner. It is also advantageous'to thoroughly lag or heat-insulate the connections 14 and 28 from the heating coils to the va.- porizing chambers, and the return connections from the reflux towers 2 and 16 including the tanks 19 and 32 to further conserve heat.

In operation, liquid residue may be discharged from the high pressure Vaporizing chamber 13 to the low pressure vaporizing chamber 25 at la rate, for example,` about 80 supplied to thev system, and about 35 to 40% of the rate at which oil is introduced to the high pressure vaporizing chamber.' A

lar e portion of this residue will be vaporize in the low pressure vaporizing chamber by reason of the reduced pressure prevailing therein and the addition heat contained in the hot oil products discharged from the heating coil 9. The residue remaining unvaporized in thelow pressure vaporizmg chamber and withdrawn therefrom as a liquid will normally amount to less than 35 to 40% of the residue discharged from the high pressure vaporizing chamber and about 30 to 35% of the fresh oil charged to the system.

The high pressure vaporizing chamber may be operated, for example, at pressures of 100 to 150 pounds per square inch or at higher pressures, and the low pressure vaporizing chamber may be operated, for example, at pressures ranging from atmospheric pressure or somewhat lower pressures up to about 50 pounds per square inch, or somewhat higher. v

The second heating zone may advantageouslybe operated at pressures of 150 to 200 pounds per square inch or at'higher pressures. K iVaporization in the low pressure Vaporizing chamber may be promoted by the introduction of steam.. The hot-oil products may be discharged from the heating coil 6 at a temperature of about 750 to 800 F. The operation ma with advantage be conducted so as to disciiarge the hot oil products from the heating coil 9 substantially in the vapor state at a temperature of about 900 to 950 F. While additional raw oil may be introduced to either of the heating coils directly, it is advantageous to introduce all, or substantially all, of the raw oil to reflux tower 2 to eifect the control and refluxing operation. Introducing all o'r substantially all of the raw oil to therefiuxing peration 1n this manner has the further advantage that the fresh oil is preheated and may also, to a certain extent, be fractionally distilled, so that the heavier and lighter portions are separated and subsequently subjected to conditions most advantageous for the cracking of those particular components.

The invention may be further illustrated by the following more speciic exam le of an operation in accordance with the invention as carried out to produce gasoline-containing cracked distillate from a gas oil character charging stock, in an apparatus of the type illustrated. The 'hea-ting furnace 53 is operated to maint-ain a discharge temperature from the heating coil 6 of about 750 to 800 F. and theheating furnace 54 to maintain a discharge temperature. from the heating coil 9 of about 900 to 950 F. The head temperature of reflux tower 1o io moiooaioooi io tho neighborhood maintained through the'reu'x tower 16 and reduced and regulatedjby means of the yalve 43. between the reliuxtower and the condenser. The heating coil 9 is operated under a pressure of about 200 pounds pery square inch, this Apressure being maintained and regulatedby means of thevalvev 2.8EL in connection 28. The low'pressure vaporizing' chamber and the reliuxtower 2 are operated under substantially atmospheric pressure. Raw oil, 31 Baume gas oil, is

supplied at a rate of about 2000 gallons perl hourand at a temperature of about`80 F.; about1600 gallons per hour ofraw'oil being introduced into the reflux tower 2 through` connection 5, and about 200 gallons per hour of raw oil being supplied d1- rectly to the heating coil 6 through connection 7, and about 200 gallons per'hour of raw oil beine* supplied directly to the heating coil 9 through connections 10 and 11.'V

Vapore pass from the high `pressure-'vaporizing chamber4 13 to the reiiux tower 16 at a temperature of about 710 F. and at a'ratev` H [of about v2600 gallons-per hour. lLoLuid vresidue-is discharged 4from the high pressure vaporizing chamber 13 to the low pressure vaporizing chamber 25 at a temperature of about 700 F. and at a rate of about 1650 gallons per hour. Reflux condensate is withdrawn from reflux tower 16 at a temperature of about 490 F. and at a rate of about 2940 gallons per hour. The Vreflux condensate fresh oil mixture from reflux tower 16 and connection 11, is supplied tol the heating coil 9 at a temperature of about 460" F. at a rate of about 3140 gallons per hour.r The vapor mixture discharged from the low pressure. vaporlzing chamber is passed to the reflux tower 2 'at a temperatureof about790 Fraud-'at a rate of about ld150{gallonsper hour. Liquid residue having 'a gravity of about 12 Baume is .Vth ojdrawn from the llow pressure vaporizing chamber at a temperature of about 780 F.

and at a rate of about 640 gallons per hour.

.l yThe mixture of redux condensate and prelim heated fresh oil is withdrawn as a liquid land .the distillate produced by subsequent condensation of .these vapors is introduced to 'reiiux tower 16 .to effect and control the reliuxing operation therein. Vapors are taken olf from reflux tower 16 at a temperature of about 400 F. at a rate of about 1360 gallons'per-hour. The distillate produced bycondensat.on of these vapors has a gravity of about 51 Baume. Where references to volumes per hour of vapors or vapor mixtures have been given in the foregoing example, it is to "be understood that the amounts given are in' terms of the amount of diquid equivalent to the amount of vapor or vapor mixture. It will alsofbe understood that .the volumes perhour, gravities and temperatures given in thev foregoing example are given only as representative of ap roximate averages.

y recycling the oil, separating as vapors in the low pressure vaporizing chamber from the liquid residue discharged from the high pressure vaporizing chamber, the present invention makes it possible to discharge from the high pressure -vaporizing chamber 'a larger proportion of the oil entering the high pressure vaporizing chamber from the heating coil as a. liquld residue without .again subjecting the unvaporized oil toI ,a -heating'operation in which heat is applied to the oil externally and without interfering with the efficiency of the o eration or the capacity of the apparatus. lso by separating in reflux tower 2 vapors liberated at the reduced pressure prevailing in the low pressure vaporizing chamber and returningthe heavier and less refractory portions to the heating zone maintained 'at the lowest temperature, and by further separating-theproducts escaping as vapors from i this reflux tower in the reflux tower 16, as described, the lighter constituents formed by thecracking operation in the heating'coil 9 are permitted to escape without` being again subjected to a cracking temperature so that over-cracking is avoided while the lighter intermediate constituents uncondensedgin reux tower 2 but condensable at the ltemperaturel maintained in reflux tower 16 are subjectedto a more severe cracking operation together with the condensate of similar naturewhich vaporizes even at the high pressure prevailing in the high pressure vaporthe heavier constituents such as may be contained in the fresh oil and heavier condensate,` of vapors liberated under conditions of cracking temperature and reduced pressure are ever subjected to the more severe cracking temperature maintained' in the heating zone 9. 1t ywill be apparent that the selective treatment of condensates of vapors from the low pressure vaporizing chamber permits an increased yield to be obtained while at the same time eliminating or greatly reducing both the tendency to izing chamber, while substantially none of 25 y f prevailing in the over-cracking and the excessive formation of coky materials. These conditions also co, operate in a particularly` advantageous inanner to greatly rolong the useful-period of4 operation. It is a further advantage of thepr'ocess of the ,invention that notwithstand- .the increased Ayields and large capacity may be obtained,''only one vaporizing j "'chamber is required which need be of the,

'expensive construction necessary tov .withstand,v high pressures at .high temperatures. f We claim:

y.1, `An improved method offcra'cking hy-:Qhy

4drocarbon oils which comprises" forcing raw. oil in a single pass throu h argheating zone into a vaporizing zone an maintaining the oil under superatmo'spheric pressure in both' the .heatingzone and the vaporizing zone,fvv heating the oil to the cracking temperature ,A forcing reflux -condensate therefrom in a .30

Isingle pass through the said heatingv zoney in ,Y .,admixture'with-raw oil,.passin reflux con- *densa'te from the said first mentioned reux- ,ing operation ,in a single ass@ throughv a separate heating 'zone'andeating vthe oil to a cracking 4temperature therein, maintaining superatmospheric pressure onvthe second mentioned heating' zonevv at s least las high'as that maintained von the first .mentioned vaporizing zone, discharging-the hot foil products from the second mentioned heating operation directly to lthe 'second mentioned va orizing zone and taking -oi vapors from oth reuxing operations.' l

2..An4 improvedmethod :fof cracking hydrocarbon oils .which comprises 'forcing raw oil in a single pass through a heating zone into -a vaporizing, zone and maintaining the oil under supei'atmospheric pressure in both the heating zone and the vaporizing zone, heating the oil to the cracking temperature in the'said heating zone, subjecting `the vapors from the said vaporizingzoneto a reuxing operation, passinglunvaporized jecting vapors from the second vaporizing kzone Ato a separate refiuxing operation ef.

fected by `heat exchange withraw-oil and lforcingA the reflux condensate therefrom in I adinixturewith the raw oil preheated thereby fin a singlepass through the said heating zone, passing reflux condensate from the said first mentioned reuxing operation in a single ing zone an heating the oil to a cracking temperature therein, maintaining superatmospheric pressure on the second mentioned v"heating zone at least as high as that maintained on the first mentioned vaporizing zone, discharging the hot oil products from the second mentionedheating operation directly to the second mentioned va'orizing zone andtaking 7off vapors from` oth refluxingoperations.. i An improved method ofcracking drocarbon-oils which comprises forcing raw oilin a single, 'pass' through a4 heating zone into avaporizing zoneand maintain- Fing the oil under superatmospheric' pressure 'in both the heating zone .and the vaporizingzone, heatin -to a-second vaporizing zone and maintaining the oil therein under a ressure lower than that prevailing in the rst vaporizing zone,y subjectingv vapors from the second 'vaporizing zone to a separate refluxing operation and introducing reiiux condensate therefrom to the said heating zone in ad- 'mixture with the raw oil, passing reflux condensate from the said first mentioned reluxing operation in a single pass through a separate heating zone and heating the oil to a higher cracking temperature in the said separate heating zone than the temperature vtowhich the oil is heated .in the first inentioned heating zone, maintaining superatmospheric pressure on the second mentioned heating zone, .dischargingthe hot oil products from the second mentioned heating operation directly to the second mentioned vaporizing zone .and taking ofi' vapors from Vboth reuxing operations. o f fifAnf improved.l method of v cracking Vhydrocarbon `oils, which comprises forcing vraw oil in a singlepass through a heating zone into a vaporing zone and-maintaining the oil under superatmospheric pressure in both the heating zone and the vaporizing zone, ,heating the oil to the cracking temperature in the said heating zone, subjecting the vapors 4from the said vaporizing zone to a retluxing operation, passing unvaporized oil from the said vaporizing zone to a second vaporizing zone and maintaining the oil therein under a pressure lower than that prevailing in the first vaporizing zone, subjecting vapors from the second vaporizing zone to a separate refluxing operation and `introducing reflux condensate therefrom to the said heating zone in admixture with the Vravv oil, passing reflux condensate from the said first mentioned refiuxing operation in a singleV pass through a separate heating zone' and heating .the oil to a cracking temc-pass through a separate heatv the oil to the crackingv tem erature in t e said heating zone, subliti 5, An improved method of cracking hy-l drocarhon oils, which comprises forcing raw oil in a single pass through a heating zone into a vaporizing zone and maintaining the oil under superatmos heric pressure in both the heating zone an the vaporizing zone, heating the oil to the cracking temperature in the said heating zone, subjecting the va ors from the said vaporizing zone to a re uxing operation, passing nnvaporized oil from the said vaporizing zone to a second vaporizing zone and maintaining the*` oil therein under al ressure lower than that prevailing in the rst yvaporizing zonexsubjecting vapors from the second vaporizing zone to a separate reiuxing operation and introducing reflux condensate therefrom to the said heating zone in admixture with the raw oil, passing reflux condensate from the said first mentioned reluxing operation in a single pass through a separate heating zone and and crack theoilinntheva or phase, discharging thejhotf. vapors rom the said separate heating zone directly to the second mentioned vaporizing zone and taking ott vapors from both retluxing operations.

' 6o An improved method of cracking hydrocarhon oils, which comprises forcing raw uoilin a single pass through a heating zone into a vaporizing zone and maintaining the oilA under superatmospheric pressure in both the heating zone and the vaporizing zone, heatingl the oil to the cracking temperature in the said heating zone, subjecting the vapors from the said vaporizing zone to a rediixing operation, passing vunvaporized oil from the said vaporizing zone to a second vaporizing Zoneand maintaining the oil therein under a ressure lower than that prevailing in the rst vaporizing zone, suhjecting vapors from the second vaporizing zone to a separate reduxing operation and introducing reflux condensate therefrom to the said heating zone in admixture with the ravv oil, passing redux condensate from the said rst mentioned reuxing operation in a single pass through a separate heating zone and heating the oil to a cracking temperature therein, maintaining superatmospheric pressure on the second mentioned heating zone at least as high as that maintained on the first mentioned vaporizing zone, dis charging the hot oil products from the seceating the oil Ttherein to vaporize v to the second mentioned vaporizing zoney taking 'od vapors from both reliuxing operations and condensing the vapors, and intro` ducing condensate of va ors escaping'from the second mentioned re uxing operation to the first mentioned reiiuxing operation.

7. An improved method of cracking hy-` in the said heating zone, subjecting the va-i pers from the said vaporizmg zone to a ref iuxing operation, passing unvaporized oit". I

from the said vaporizing zone to a second vaporizing zone and maintaining the therein under a prevailing in the rst vaporizing zone, subjecting vapors from the second vaporizing zone to a separate reuxing operation efected by heat exchange with raw oil and. introressure lowerv than that ducing the reflux condensate therefrom in admixture with theraw oil preheatedtherehy. to the said heating zone, passing redux condensate from the said first mentioned refluxing operation in a single pass through a separate heating zone, maintaining superatmospheric pressure in the said separate heating zone and heating the oil therein to a higher cracking temperature than the temperature to which the oil is heated 'in the first mentioned heating zonexdischargin the hot oil products from the said se arate eating zone directly to the secon mentioned vaporizing zone, taking oi` vapors from hoth retluxing operations and condensing the va pors, introducing condensate of vapors escaping from the second mentioned reHuXing operation, and discharging unvaporized residue from the second mentioned vaporizing zone.

8. An improved method of cracking hydrocarbon oils, which comprises forcing oil in a single pass through a heating zone into a vaporizing zone and maintaining the oil under superatmospheric pressure in hoth the heating zone and the vaporizing zone, heating the oil to the cracking temperature in the said heating zone, subjecting vapors from the said vaporizing zone to areluxin operation, passing unvaporized oil from the said vaporizing zone to a second vaporizing zone and maintaining the oil therein under a pressure lower than that prevailing in the first vaporizing zone, subjecting the vapors from the second vaporizing zone to a separate reliuxing operation, introducing ravtr oil to the separate reiiuxing operation7 and supplying reflux condensate and admixed unvaporized oil together With an independent supply of ravv oil to the, Said ond mentioned heating operation directly h eating zone, passing redux condensate from the said irst mentioned reiuxing operation in a single pass through a separate heating zone and heating the oil therein to a higher cracking temperature in the said separate heating zone than the temperature to which the oil is heated in the first mentioned heating zone, discharging the hot oil products from the second mentioned heating opera.-

t`ion directly to the second mentioned vaporizing zone and taking off vapors from both reuxing operations.

In witness whereof, we have subscribed our names.

EUGENE C. HERTHEL. THOMAS DE COLON TIFFT. 

